Hi Pekka, On Thu, 2003-08-07 at 17:47, Pekka Savola wrote: > On Thu, 7 Aug 2003, Andrew White wrote: > > > Just responding to a few points.. > > > > Real example: My ISP's DSL connection decides to drop the connection and > > reconnect (with a new IPv4 address, and thus 6to4 prefix) every 1-3 hours. > > I'd rather not subject my internal network to that if I don't have to. > > Switch ISP or complain to them. I certainly wouldn't bear with that kind > of behaviour. > > If that kind of ISP techniques are commonplace, we may need to do > something. But I'm not sure if that's the case. Experiences? >
Here in Australia, the former government monopoly, now pseudo-government (50.(something)%) / private (49.(something)%) telco, Telstra, owns the CAN, which is used for pretty much all residential (at least probably 99%) ADSL. Telstra use the ADSL network for both their own retail residential customers, as well as wholesaling it to other ISPs, large and small. Since the realisation that dial-up was a dying technology, a lot of the dial up ISPs are providing ADSL, wholesaling it from Telstra. According to this page (http://www.broadbandchoice.com.au/isp-list.cfm), there are currently 149 residential ISPs in Australia, which is probably quite a lot for a country with only 20 million or so people. A typical residential ADSL service is : * Single IPv4 address, so you have to use NAT if you want more than one machine (although at least one enlightened ISP allows up to 8 PPP(oE|oA) logins at once on a single ADSL service) * A download cap eg 1000MB, 4000MB, etc. per month, with extra MB charged at around $0.15 each etc * The single IPv4 address can change over time. Most ISPs don't specify the time period, and it varies, but I expect that having the same single IPv4 address for a week is starting to be an an exception, rather than a rule. Some ISPs have introduced "unlimited" download plans, where, over a rolling period, the more you download, the less priority your packets get against other customers traffic. A lot of these ISPs also want to provide business ADSL over the same wholesaled ADSL infrastructure. They typically do this by : * Guaranteeing a single IPv4 address, that won't change. * Optionally routing a prefix for the customer LAN ie. no NAT. A lot of small business customers probably don't take this up, probably because they are told about the "security" using NAT. I'd suspect in most cases not having to change internal IPv4 addressing is not even a "NAT or not" consideration. * Providing a different helpdesk ph#, with shorter response times. * Providing much lower download caps, to make more revenue on business users downloading data. Of course, they also charge a lot more for the business service, typically twice as much or more, than the residential ADSL service. Apparently, a lot of small businesses are going with residential plans, as they don't find the business plan differences to be worth the money. (http://whirlpool.net.au/article.cfm?id=1165&show=replies) A lot of residential users, such as myself, get around some of the changing IPv4 address issues by using dynamic DNS services, such as http://www.dyndns.org. I run a client on my linux server, which watches the ppp0 interface. When the IPv4 address changes, it goes and updates the corresponding DNS RR with the new IPv4 address information. The TTL on the RRs is 60s. It would seem that a lot of residential ADSL users want to have domain names to the point where some ADSL router vendors are even building dynamic DNS clients into their devices. (ps, being a purist (or just enlightened maybe) I don't run NAT. I only have one PC that I want connected to the Internet, though, so I don't need to either.) > Note: consider how many of these techniques are used to prevent people > from keeping servers at their home systems (i.e., does the ISP consider > the changing address a bug or feature). Certainly a feature. ISPs quickly learnt not to filter incoming TCP / UDP ports to prevent people running "servers", http or otherwise, so they use the reliability of the single IPv4 address they allocate as a dis-incentive to running a "server". "Uploads" typically aren't capped, so you could run a heavily trafficed server, with only the client's TCP Acks contributing to your download quota. Of course TCP Acks are pretty small, you can fit a lot of them within a monthly quota of 1000 or 4000 MB. Also consider how the situation > would change (if any) with IPv6 provided by the ISP. > I'd suspect they would probably allocate periodically changing /128s to their residential ADSL users. Of course, 6to4 is a way around that, but it probably won't take them long to wise up and start filtering that. > Real example: at home, I use DHCP on DSL to get addresses. During 1 year, > the addresses have changed _once_ (the ISP changed the prefix from which > it allocated the DSL users' addresses). That's good enough for me, and I > even manually glue all the IPv4 and resulting 6to4 addresses in my > configuration files, filters etc. So what is the weather like in Finland ? I might consider moving :-) Hope my (long winded) description is useful, Mark. -------------------------------------------------------------------- IETF IPng Working Group Mailing List IPng Home Page: http://playground.sun.com/ipng FTP archive: ftp://playground.sun.com/pub/ipng Direct all administrative requests to [EMAIL PROTECTED] --------------------------------------------------------------------
